Electric safety-fuse.



T. E.v MURRAY. ELECTRIC SAFETY. FUSE. 'nrmouxon nun 11.13.11. 1900.

Patented Apr. 26, 1910.

. ituemc'o:

THOMAS ,E. MURRAY, or NEW YORK, n. Y.

ELECTRIC SAFETY-FUSE.

Specification of Letters Patent.

Patented Apr. 26, 1910.

Application filed March 11, 1909. Serial No. 482,697.

- T 0 all whom it may concern:

claimed anelectric' safet fuse comprising a tubular case integrally ormed of porcelain or other fictile material, a fuse strip therein, and a filling of non-combustible material completely occupying the space-within the case and protectinglsaid case from the effects of explosion of -t e fuse, by mechanically dampenin the shock of said explosion. I have foun that where the ends of the case are closed by metallic caps or the like forming joints with the case, under certain conditions, moisture may enter said case through said joints and be retained by the commi- I nuted filling material. In such event, the

blowing of the fuse strip instantly converts said moisture into steam, with the result that the case may become ruptured, by the sudden pressure, even when competent to resist the shock of fuse explosion if the filling material be dry.

My invention has forits object to remove this difficulty, and consists in the construction hereinafter set forth, whereby the.ends' of the fuse case are closed by plugs of noncombustible material introduced in a plastic state and becoming hard by setting and simultaneouslyslightly expanding in volume, thus forming a perfectly close joint, the said plugs being also rendered impervious by coating their exposed faces with a material impervious to moisture.

1n the accompanying drawings Figurel is a longitudinal section ofi'ny eleotrlc fuse, and Fi 2 is an end view.

Simi ar letters of reference indicate like parts. I I

A is the tubular'case integrall formed of fictile material, preferably poroe ain.

B is the fuse strip which extends through the case and is embedded in-any non-com bustible comminutecl material C, such as plaster, which material completely fills the. case and operates to protect the case from rupture on the blowing of the fuse by dampening the shock of the explosion. In the ends of the case I insert plugs D of, preferably, plaster of paris tempered with water to the plastic state, or any other plastic material which is non-combustible and which hardens by setting. I prefer plaster of paris because in settin it expands somewhat in volume and thus forms a tight joint with the case. Said plugs are rendered moisture proof by coating their exterior faces, after setting, with a layer E of shellac or other materlal impervious to moisture.

I claim:

1.'In a safety fuse, a tubular case integrally formed of fictile material, end plugs of non-combustible material in saidoase introduced in plastic state and hardened in place by setting, a fuse strip extending between and through said plugs, and a body of non-combustible material completely fillin the remaining space within said case and constructed to dampen or retard the vibrations due to sudden shock of explosion, and thereby prevent rupture of said case.

2. In a safety fuse, a tubular case integrally formed of fictile material, end plugs of non-combustible material in said case introduced in plastic state and hardened in place by setting, a moisture proof coating on the exposed faces of said plugs, a fusestrip extending between and through said plugs, and a body of non-combustible material completely filling the remainin space within said case and constructed to dampen or retard the vibrations due to sudden shock of explosion, and thereby prevent rupture of said case.

In testimony whereof I have afiixed my signature in presence of two witnesses.

THOMAS E. MURRAY. 

